package com.SuanFa.test;

import java.util.Scanner;

public class test1 {
    public static void main(String[] args) {
        Scanner sc=new Scanner(System.in);
        double i = sc.nextDouble();
        double temp=2;
        int a=0;
        double temp1=2;
        while (temp1<i){
            temp=temp*0.98;
            temp1+=temp;
            if (temp1>=i){
                System.out.println(a+2);
                break;
            }
            a++;
        }
    }
}
